Electric field–prevented adsorption of hydrogen on supported gold nanoparticles
The adsorption of hydrogen on the surface of gold nanoparticles deposited on a graphite support was studied in the presence of an external electric field by means of scanning tunneling microscopy (STM) and spectroscopy (STS). Hydrogen was adsorbed from the gas phase onto the surface of gold nanoparticles synthesized by impregnation-precipitation method. During the adsorption process, the STM tip was removed from the surface of the sample so that the measurable tunneling current could not flow, and potential differences of various polarities were applied to the vacuum gap between the sample and the grounded tip. Thus, the system of the STM tip and sample surface formed an asymmetric capacitor inside which an inhomogeneous electric field existed. No hydrogen adsorption was observed in the case of a positive potential difference, while dissociative adsorption of hydrogen took place in the cases of zero and negative potential differences. The ability to control the adsorption process of hydrogen by means of a weak electric field was demonstrated.
KeywordsGold nanoparticle Hydrogen Dissociative chemisorption Electric field Scanning tunneling microscopy
scanning tunneling microscopy
scanning tunneling spectroscopy
highly oriented pyrolytic graphite
Fourier transform infrared spectroscopy
current-voltage dependences measured at the tip nanojunction with HOPG
current-voltage dependences measured at the tip nanojunction with the nanoparticles
lowest unoccupied molecular orbital
AKG carried out the experiments. MVG drafted the manuscript. SYuS and VAKh participated in the measurements and performed the analysis. BRSh supervised the overall study and edited the manuscript. NNK and NVD prepared and edited the theoretical section. All the authors have read and approved the final manuscript.
This work was supported by the Russian Foundation for Basic Research, grant nos. 16-29-05119, 16-03-00046, 17-03-00275, 18-03-00060, and 18-33-00020.
Compliance with ethical standards
The authors declare that they have no competing interests.
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